Sunday, 25 November 2012

Optical Imaging- A tool to monitor Progression

Epub: Herrero et al. Progressive degeneration of the retinal nerve fiber layer in patients with multiple sclerosis. Invest Ophthalmol Vis Sci. 2012 Nov. doi:pii: iovs.12-10362v1. 10.1167/iovs.12-10362.

PURPOSE: To quantify changes in the retinal nerve fiber layer (RNFL) of patients with multiple sclerosis (MS) over 3 years and to evaluate whether treatment protects against RNFL degeneration. 

METHODS: Ninety-four MS patients and 50 healthy subjects were followed-up over 3 years. All subjects underwent a complete ophthalmic examination, which included assessment of visual acuity (Snellen chart), color vision (Ishihara pseudoisochromatic plates), visual field examination, optical coherence tomography (OCT), and visual evoked potentials (VEP. Shine a light in the eye and measure the brain electrical activity in the brain). All patients were re-evaluated at 12, 24, and 36 months to quantify changes in the RNFL. 

RESULTS: Changes were detected in RNFL thickness at the 36-month follow-up. Significant decreases (P<0.05, t test) were observed in the mean, superior (top), inferior (bottom), temporal (Outside) RNFL thicknesses, and macular volume (bit where vision is focused) provided by OCT, and in the P100 latency of VEP (Speed of nerve impulse) of the MS group; but only in the mean and inferior  (inside) RNFL thickness of the healthy control group. Greater changes in the superior and inferior RNFL thickness during follow-up were detected in the MS group. Differences between treatments were not detected, but untreated patients had higher degeneration in the mean and superior RNFL thickness during the follow-up (p= 0.040 and p=0.19, respectively). 

CONCLUSIONS: Progressive axonal loss can be detected in the optic nerve fiber layer of MS patients. Analysis of the RNFL by OCT can be useful for evaluating MS progression and efficacy of treatment as a neuroprotective factor against axonal degeneration.
Ishihara Plate
Schnellen Chart
                                   
We have previously posted on what OCT is and how it can detect retinal degeneration. There are changes in the nerve fibres in the eye irrespective of whether you have had optic neuritis. Often it is reflective of more brain activity of lesions. The treatment effect or lack of it showed a tendency for benefit but as it was not signficant we say showed no benefit. However, the interferons have not been reported to inhibit non-relapsing progression. This is another tool at the disposal of the neuro, but if there is a small change seem over 3 years, would this give advantage over looking for a clinical outcome if it takes so long?

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